A wierd OO problem

Anon

<pre>
<?
class Parent {
function Parent(){
$this->baseObj = &$this;
}

function insert($name){ 				$this->baseObj->test[$name] = new Child();
	$this->baseObj->test[$name]->baseObj = &$this->baseObj; 
}

}

class Child extends Parent{
function Child(){
$this->whatever = 'sometext'; }
}

$obj = new Parent();
$obj->insert('foo'); $obj->test['foo']->insert('bar');
$obj->test['bar']->insert('blah');
?>
</pre>

This code outputs

Fatal error: Call to a member function on a non-object in /www/htdocs/HTModule/classtest.php on line 28

Line 28 ($obj->test['foo']->insert('bar')😉 is when a new child is to be inserted into the child 'foo', stored in the test property in Parent.

The wierd thing is, this worked fine until I installed the latest PHP version (4.0.2), I had 4.0.1RC. I can't imagine that that would make a difference and I didn't see anything in the changelog that would indicate any changes to objects like this. It seems so simple, yet I'm dumbfounded.

I have read other posts with similar problems, but mostly people aren't trying to store objects inside other objects like this.

As far as I can tell, giving each child a reference back to the parent is the only way that the child objects would be able to communicate back while still inheriting insert().

Any help is greatly appreciated.

Thanks in advance,
Dave

Anon

Your code is rather screwey. It probably worked in a old version of PHP because whatever allowed it has since been fixed to work right.

Exactly what are you trying to do? Create shared variables from the ancestor of child?

If you can explain what your objective is, you'll have a better chance at people suggesting options.

Anon

It's really not that screwy. The parent class contains a method, insert() which instantiates child classes and stores them in an array which is one of its properties. When a child class calls the inherited insert() method, the created object is still stored in the parent's array, no matter how deeply they are nested, the objects can still be easily accessed through the parent's property by index, since they are indexed by name.

Why do this? I'm building a set of classes to render HTML. About a year (or 2?) ago, there was an article on this site about class.layout, a class for creating complex HTML layouts. Each tag is represented by an object, and objects (tags) are inserted inside one another. When the HTML is rendered, it goes to the parent, prints its start tag, then goes through the children, prints each of its children recursively then prints its end tag.

Well I liked the idea of class.layout, even though it seemed more complex than nessesary. I'm doing a project where so much in the HTML had to be scripted, it made it almost impossible to just use simple templates. One example is a DHML popup menu. This requires 3 things, HTML, JavaScript and Stylesheets. Well, if I want to be able to add the menu dynamically, I had to have logic in three places to put in the code to make it work (or create functions for each section). By making the entire HTML page non-linear, I can create the logic to add the menu all in one place and insert the code where needed, and I never have to write HTML.

Its not as crazy as it sounds, because it allows you to do some great things, such as creating default attributes for tags and render the HTML according to the type of browser used for consistancy. This allows you to create user customizable sites very easily.

The basic problem is: why, if the parent has a property which is a reference to itself (its instance) can't it pass that reference to its children in the way I have described.